Fibrosis of the liver can be caused by activated hepatic stellate cells (HSC), resulting in a plurality of types of collagen molecules and fibronectin being deposited on interstitial tissue. This can lead to hepatic cirrhosis, hepatic failure, and/or hepatocellular carcinoma. Further, chronic pancreatitis develops as a result of pancreatic fibrosis by the same mechanism as that for hepatic fibrosis (Madro, 2004, Med Sci Monit, 10:RA166-70; Jaster, 2004, Mol Cancer, 6:26). Furthermore, stellate cells are present in the vocal cord disorders of the vocal cord and larynx such as vocal cord scarring, vocal cord mucosal fibrosis, and laryngeal fibrosis. To prevent or treat fibrosis in these organs and elsewhere in the body, there is a desire for the development of a drug carrier.
Stellate cells are one of the important target candidates for treating fibrosis (Fallowfield, 2004, Expert Opin Ther Targets, 8:423-35; Pinzani, 2004, Dig Liver Dis, 36:231-42). During fibrosis, stellate cells are activated by cytokines from nearby cells and are activated. Stellate cells are known as storage cells for vitamin A, and belong to the myofibroblast family, and produce many factors that cause hepatic fibrosis.
Therapeutic methods to prevent or treat fibrosis attempt to control collagen metabolism, promotion of the collagen degradation system, and inhibition of activation of stellate cells. However, in all cases, since the specificity of action and/or the organ specificity are low, there are problems with the limited efficacy and with adverse side effects.
Inhibition of collagen protein synthesis has not been established as a therapeutic method. The potency of molecules targeting collagen production is limited because of the possibility of causing side effects. Inhibiting collagen production directly would be an obvious therapeutic method to prevent or treat fibrosis. To do this would require control of one or more of the various types of collagen Types I to IV. A method for accomplishing this may be through HSP47, a collagen-specific molecular chaperone that is essential for intracellular transport and molecular maturation necessary for various types of collagen. Therefore, if in stellate cells the function of HSP47 can be controlled specifically, there is a possibility of inhibiting hepatic fibrosis.